The 14th Overture Workshop: Towards Analytical Tool Chains

This report contains the proceedings from the 14th Overture workshop organized in connection with the Formal Methods 2016 symposium. This includes nine papers describing different technological progress in relation to the Overture/VDM tool support and its connection with other tools such as Crescendo, Symphony, INTO-CPS, TASTE and ViennaTalk

Prise en compte des systèmes de stockage de l'énergie et de leurs dégradations dans la gestion et le dimensionnement des micro-réseaux : influence de la précision des modèles

Le développement de micro-réseaux électriques, stationnaires, décentralisés et distribués, produisant l'énergie au plus près des consommateurs, est une des solutions possibles pour assurer l'intégration des énergies renouvelables qui est aujourd'hui un défi clé de la transition énergétique. Les Systèmes de Stockage de l'Énergie (SSE) au sein des micro-réseaux vont permettre de pallier l'intermittence et le manque d'inertie de ces sources renouvelables en apportant la flexibilité nécessaire ainsi que des possibilités d'optimisation des échanges d'énergie en fonction de critères économiques et écologiques. Les batteries sont les SSE les plus utilisées dans les micro-réseaux mais restent des éléments coûteux avec une durée de vie relativement faible et un impact écologique important. L'objectif global de la conception d'un micro-réseau revient à optimiser le dimensionnement des sources et des batteries (taille, technologie et topologie) en lien avec les stratégies de gestion de l'énergie. Pour cela, de nombreux outils et études existent et utilisent des modèles de fonctionnement et de vieillissement des batteries. Cependant, peu de travaux évaluent la précision de ces modèles dans des conditions réelles de fonctionnement, ni leurs impacts sur la qualité du dimensionnement ou de la gestion qui en découlent. La voie de recherche choisie dans cette thèse consiste en l'analyse de l'influence des modèles de SSE sur la conception optimale de micro-réseaux. Parmi les deux familles de batteries majoritaires dans les applications stationnaires qui sont les batteries Plomb-Acide et Lithium-ion, un focus sur la technologie Plomb-Acide a été réalisé, cette technologie présentant une grande maturité et un bon taux de recyclabilité. L'objectif est d'évaluer l'aptitude des modèles à prendre en compte le fonctionnement des SSE, à traduire les usages amenant des dégradations et à s'intégrer dans un environnement de modélisation pour l'optimisation multicritères (coût, usage de l'énergie produite localement, durée de vie) du dimensionnement et le développement de stratégies de gestion de l'énergie. Pour valider ces travaux, un banc de test de type micro-réseau basse tension continue a été réalisé. Ce banc permet d'émuler un micro-réseau à partir de données réelles de production et de consommation et, ainsi, évaluer le comportement des SSE dans des conditions maîtrisées mais proches d'un fonctionnement réel. Une étude comparative de modèles de batteries a ensuite été faite pour déterminer le plus approprié à la conception de micro-réseaux. L'analyse de la précision des modèles a été réalisée afin d'étudier leurs aptitudes à représenter le comportement des batteries et à traduire les phénomènes ayant un impact sur leur durée de vie. Pour cela, des profils d'usages liés aux micro-réseaux ont été identifiés et générés à partir des données du bâtiment à énergie optimisée du LAAS-CNRS. Enfin, à partir de ces modèles, une méthodologie pour dimensionner les sources et les SSE dans un micro-réseau est proposée. Ces mêmes modèles ont été utilisés pour mettre en œuvre des stratégies de gestion optimales. Dans les deux cas, une recherche de l'impact des modèles sur les résultats obtenus a été faite. Puis, les stratégies de gestion ont été testées sur le banc de test développé afin d'observer le comportement réel des SSE et les limites du modèle face aux résultats expérimentaux.The development of decentralized, distributed, stationary electric microgrids producing energy as close as possible to the consumers, is a key challenge of the energy transition. Microgrids can contribute to the massive renewables energies integration and allow the optimization of the energy use according to several economic and ecological criteria. Batteries are the most widely used Energy Storage Systems (ESS) in microgrids, but are among the most expensive components with a relatively short lifetime. Therefore, optimize the sizing of sources and batteries (sizes, technologies and topologies) considering the energy management strategies is the general objective of the optimal design of a microgrid. For this purpose, many tools and studies exist using battery behavior and aging models. However, few works evaluate the accuracy of these models in real operating conditions, nor their impacts on the resulting sizing or energy management decisions. The research path chosen in this thesis consists in the analysis of different ESS models, considering their operation and degradation and used in optimal microgrid design methods. The objective is to evaluate the ability of these models to be integrated in a modeling environment dedicated to multi-criteria optimization (cost, use of locally produced energy, lifetime...) to size microgrids and develop energy management strategies. To validate this work, a test bench of a low voltage DC microgrid type has been built. This bench allows to emulate a microgrid from real production and consumption data and thus to evaluate the behavior of the ESS under controlled conditions but close to a real operation. A comparative study of battery models has been then made to find the most appropriate ones for microgrids design. An analysis of the accuracy of these models was carried out in order to study their ability to represent the battery behavior and the typical variations related to the stresses impacting their life span. For this purpose, usage profiles related to microgrids have been identified and applied to lead-acid batteries, widely used in stationary applications. Finally, based on these models, a methodology for sizing sources and ESS in a microgrid is proposed. These same models were used to implement optimal management strategies. In both cases, an investigation of the impact of the models on the results obtained was done. Then, the management strategies were tested on the developed microgrid testbed in order to identify the impact of the model in the differences between the simulation and experimental results

PV System Design and Performance

Photovoltaic solar energy technology (PV) has been developing rapidly in the past decades, leading to a multi-billion-dollar global market. It is of paramount importance that PV systems function properly, which requires the generation of expected energy both for small-scale systems that consist of a few solar modules and for very large-scale systems containing millions of modules. This book increases the understanding of the issues relevant to PV system design and correlated performance; moreover, it contains research from scholars across the globe in the fields of data analysis and data mapping for the optimal performance of PV systems, faults analysis, various causes for energy loss, and design and integration issues. The chapters in this book demonstrate the importance of designing and properly monitoring photovoltaic systems in the field in order to ensure continued good performance

Proceedings of the NASA Conference on Space Telerobotics, volume 1

The theme of the Conference was man-machine collaboration in space. Topics addressed include: redundant manipulators; man-machine systems; telerobot architecture; remote sensing and planning; navigation; neural networks; fundamental AI research; and reasoning under uncertainty

New optimized electrical architectures of photovoltaic generators with high conversion efficiency

L'objectif de cette thèse est l'optimisation du rendement des chaînes de conversion photovoltaïques (PV). Différentes améliorations de l'architecture électriques et de ses algorithmes de commande ont été développées afin d'obtenir un haut rendement de conversion sur une grande plage de puissance d'entrée. Ces travaux portent également sur l'allongement de la durée de vie de l'étage de conversion électrique. Les avantages et les inconvénients d'un système composé de convertisseurs connectés en parallèle ont été montrés notamment à travers une analyse de pertes. Ces études ont permis la conception d'une nouvelle architecture constituée par des convertisseurs parallélisés. Cette dernière est appelée "Convertisseur Multi-Phase Adaptative" (MPAC). Sa singularité réside dans ses algorithmes de commande qui adaptent les phases actives selon la production de puissance en temps réel et recherchent la configuration la plus efficiente à chaque instant. De cette façon, le MPAC garantit un haut rendement de conversion sur toute la plage de puissance de fonctionnement. Une autre loi de commande permet quant à elle d'uniformiser le temps de fonctionnement de chaque phase par l'implémentation d'un algorithme de rotation de phase. Ainsi, le stress des composants de ces phases est maintenu homogène, assurant un vieillissement homogène pour chacune des phases. Etant donné alors le faible stress appliqué sur chaque composant, la structure MPAC présente une durée de vie plus importante. Les améliorations de l'étage de conversion de puissance ont pu montrer par la réalisation d'un prototype expérimental et par la réalisation de tests expérimentaux la validation globale du système. Pour finir, des tests comparatifs entre une chaîne de conversion PV classique et notre système ont montré une amélioration significative du rendement de conversion.This thesis focuses in the optimization of the efficiency of photovoltaic power conversion chain. In this way, different improvements have been proposed in the electrical architecture and its control algorithms in order to obtain high efficiency in a large rage of input power and long life-time of PV power conversion system. Using loss analysis, the benefits and drawbacks of parallel connection of power structures has been shown. This analysis has allowed the conception of a new optimized architecture constituted by parallelized power converters, called Multi-Phase Adaptive Converter (MPAC). The singularity of these power structures consists on the adaptation of the phases of the converter depending on the power production in real-time and looking for the most efficient configuration all time. In this way, the MPAC guarantees high conversion efficiency for all power ranges. Another control law is also implemented which guarantees a rotation of the phases to keep their working time uniform. Thus, the stress of the components of all the phases is kept homogenous, assuring a homogeneous aging of the phases. Since the global stress of the component is lower, the MPAC presents a longer life-time. The improvements in the power conversion stage are shown by experimental prototypes. Experimental tests have been done for global validation. Comparison with a classical power conversion stage shows the improvement in the global conversion efficiency

Water Stewardship

Achieving true wholesome sustainability requires a change of heart. Hence this book starts in the heart. It asks the timely question of ‘how do we become true water stewards?’ The transformation to a new sustainable practice will be made through a new connection with our heart, a more holistic type of analysis (brains) and the right actions based on personal integrity (hand). A water steward should be similar to the shepherds of olden days. They were given the responsibility to guard the sheep. The village trusted they would take care of the herd, make sure it would be well fed, protected from storms and kept together. The shepherd learned to take a long term perspective for the herd, ensuring that the pastures were not overgrazed, that the herd was not led too far away from access to water and that shelter was in reach in the event of storms and dangerous predators. Over time the shepherds became increasingly skilled in caring for the herd. They integrated the responsibility of the well-being of the herd into their identity. In a similar way, we can take the responsibility for human water consumption and our interaction with the natural world. We need to understand and work according to the big picture and the very long term perspective. Being a water steward requires deep reflection of how water should be treated and our relationship with water. Water utility professionals have the knowledge and have been trusted with the role of managing human water consumption. This is a great responsibility and requires deep reflection of how this should be done. The book will present ideas and concepts for the new role as well as questions for personal reflection

From RF-Microsystem Technology to RF-Nanotechnology

The RF microsystem technology is believed to introduce a paradigm switch in the wireless revolution. Although only few companies are to date doing successful business with RF-MEMS, and on a case-by-case basis, important issues need yet to be addressed in order to maximize yield and performance stability and hence, outperform alternative competitive technologies (e.g. ferroelectric, SoS, SOI,…). Namely the behavior instability associated to: 1) internal stresses of the free standing thin layers (metal and/or dielectric) and 2) the mechanical contact degradation, be it ohmic or capacitive, which may occur due to low forces, on small areas, and while handling severe current densities.The investigation and understanding of these complex scenario, has been the core of theoretical and experimental investigations carried out in the framework of the research activity that will be presented here. The reported results encompass activities which go from coupled physics (multiphysics) modeling, to the development of experimental platforms intended to tackles the underlying physics of failure. Several original findings on RF-MEMS reliability in particular with respect to the major failure mechanisms such as dielectric charging, metal contact degradation and thermal induced phenomena have been obtained. The original use of advanced experimental setup (surface scanning microscopy, light interferometer profilometry) has allowed the definition of innovative methodology capable to isolate and separately tackle the different degradation phenomena under arbitrary working conditions. This has finally permitted on the one hand to shed some light on possible optimization (e.g. packaging) conditions, and on the other to explore the limits of microsystem technology down to the nanoscale. At nanoscale indeed many phenomena take place and can be exploited to either enhance conventional functionalities and performances (e.g. miniaturization, speed or frequency) or introduce new ones (e.g. ballistic transport). At nanoscale, moreover, many phenomena exhibit their most interesting properties in the RF spectrum (e.g. micromechanical resonances). Owing to the fact that today’s minimum manufacturable features have sizes comparable with the fundamental technological limits (e.g. surface roughness, metal grain size, …), the next generation of smart systems requires a switching paradigm on how new miniaturized components are conceived and fabricated. In fact endowed by superior electrical and mechanical performances, novel nanostructured materials (e.g. carbon based, as carbon nanotube (CNT) and graphene) may provide an answer to this endeavor. Extensively studied in the DC and in the optical range, the studies engaged in LAAS have been among the first to target microwave and millimiterwave transport properties in carbon-based material paving the way toward RF nanodevices. Preliminary modeling study performed on original test structures have highlighted the possibility to implement novel functionalities such as the coupling between the electromagnetic (RF) and microelectromechanical energy in vibrating CNT (toward the nanoradio) or the high speed detection based on ballistic transport in graphene three-terminal junction (TTJ). At the same time these study have contributed to identify the several challenges still laying ahead such as the development of adequate design and modeling tools (ballistic/diffusive, multiphysics and large scale factor) and practical implementation issues such as the effects of material quality and graphene-metal contact on the electrical transport. These subjects are the focus of presently on-going and future research activities and may represent a cornerstone of future wireless applications from microwave up to the THz range